Electrical connector having improved locking means



Dec. 29, 1970 R. G- HARTWELL 3,5513% v ELECTRICAL CONNECTOR HAVINGIMPROVED LOCKING MEANS 2 Sheets-Sheet 1 Filedzsept. 23, 1968 Dec. 29,1970 HARTwE-LL 3,551,889

ELECTRICAL CONNECTOR HAVING IMPROVED LOCKING MEANS Filed Sept. 23, 19682 Sheets-Sheet 2 United States Patent U.S. Cl. 339-89 4 Claims ABSTRACTOF THE DISCLOSURE Multi-contact electrical connector comprisescylindrical plug and cylindrical socket or receptacle having hood eX-tending therefrom which is adapted to receive the plug. Both parts aremolded of a relatively firm insulating ma terial such as polycarbonateor a modified polysulfone and have contacts mounted in their bodyportions which are engaged with each other when the connector parts arecoupled. Hood portion of the receptacle has an axially extending slotand plug portion has a radially extending boss which is adapted to moveinto the slot when the parts are engaged with each other. A locking ringis mounted rotatably on the hood for rotation in its own plane and has anotch therein which, when the locking ring is in one position, permitspassage of the boss or car on the plug and which, when in a secondposition, prevents movement of the boss past the plane of the lockingring. The locking ring thereby functions to hold the parts in assembledrelationship and prevents accidental disengagement.

BACKGROUND OF THE INVENTION The instant invention relates to circularconnectors of the type comprising a plug and a receptacle, thereceptacle having a circular hood extending from its mating face whichhood is adapted to receive the plug when the parts are engaged with eachother. The connectors of this type which are commonly available vusuallyhave metal shells for both the plug and the receptacle within whichinserts of insulating material are mounted, the inserts in turncontaining the contact terminals by means of which the electricalconnections are made when the parts of the connector are engaged witheach other. It isalso common in connectors of this type to provide acoupling or locking ring on the hood of the receptacle portion, thefunction of this nut being to draw the parts together while they arebeing engaged and to hold them in assembled relationship thereby toprevent accidental decoupling of the parts. Circular connectors of thetype described above are extremely rugged and highly reliable althoughtheyare relatively expensive because of the fact that each connectorpart comprises both a metal shell and an insulating insert which must bemounted in the shell.

The present invention is directedv to the achievement of a relativelylow cost circular connector having most, if not all, of the desirablefeatures of presently available connectors of this type. It isaccordingly an object of the invention to provide an improved circularconnectonA further. object is to provide. a connector structure havingprincipal parts'which can be manufactured by conventional moldingprocesses. A still further object is to provide a connector having alockingring which can be assembled to the "receptacle portion of theconnector by a relatively simple assembling step. A still further objectis to provide a molded connector of a relatively high quality plasticmaterial such as polycarbonate which is resistant to adverseenvironmental conditions and which will withstand abusive usage withoutdeterioration of its electrical function.

These and other objects of the invention are achieved in a preferredembodiment thereof comprising a connector plug and a connectorreceptacle, the plug comprising a simple molded cylinder ofpolycarbonate, a modified polysulfone, or similar material, having aplurality of contact receiving cavities extending therethrough from itsrearward face to its mating face and having contact sockets mounted inthese cavities. The receptacle part of the connector assembly comprisesa generally cylindrical body portion having cavities therein in whichcontact pins are mounted which are adapted to make the contact socketsof the plug portion of the connector assembly. A circular hood extendsfrom the mating face of the receptacle in surrounding relationship tothe projecting ends of the contact pins, the inside diameter of thishood being such that it will relatively snugly receive the plug when theparts are engaged with each other. The plug portion of the connectorassembly is provided with a radially extending boss or car adjacent toits mating face and a slot is pro- .vided in the hood of the receptaclewhich is adapted to receive this car. This slot and ear arrangementthereby functions to polarize the connector parts when they are engaged.A relatively simple locking ring is rotatably mounted on the externalsurface of the hood of the re ceptacle part and has a radially extendingnotch on its inside edge. When this notch is in alignment with the slotin the hood, the parts can be engaged with each other since the ear orboss on the plug will be permitted to move past the plane of thecoupling ring. After the parts have been substantially completelyengaged with each other, the locking ring is rotated so that laterallyfacing surface portions of the ring are against the ear or boss on theplug part of the connector. When the ring is in its rotated position, itthus prevents unintentional or accidental separation of the connectorparts from each other.

In the drawings:

FIG. 1 is a perspective view of a preferred form of connector assemblyin accordance with the invention showing the parts in alignment with,but separated from, each other;

FIG. 2 is a perspective view of the receptacle portion of the connectorwith the locking ring exploded from the receptacle hood and illustratingthe manner in which the locking ring is assembled to the hood;

FIG. 3 is an end view of the mating face of the receptacle portion ofthe connector and showing the relative position of the locking ringimmediately after it hasbeen mounted on the hood of the receptacle butprior to its being rotated to its assembled position;

FIG. 4 is a view similar to FIG. 3 but showing the relative position ofthe locking ring after it has been rotated to its assembled position;

FIG. 5 is a side view of the connector assembly in accordance with theinvention.

A preferred form of connector assembly in accordance with the inventioncomprises a plug part 2 and a receptacle part 4, each of these partscomprising a unitary molding of a relatively high quality, relativelyfirm plastic insulating material such as a polycarbonate or a modifiedpolysulfone as described below. The plug 2 has a plurality of contactreceiving cavities 6 extending from its rearward side 8 axiallytherethrough to its mating face 10, these cavities being adapted toreceive contact terminals 12 in the form of conventional contactsockets. These sockets are crimped or otherwise secured to conductors 14which extend from the rearward side of the connector body and which aresupported on the upper surface of an arcuate flange 16 which is integralwith, and which extends rearwardly from, the rearward side of theconnector. A pair of spaced apart openings 18 are provided in the flange16 adjacent to its end and a suitable clamping means extends around theconductors 14 and through these openings to clamp the conductors againstthe surface of the flange and function as a strain relief for the 3conductors. In the disclosed embodiment, this clamping means comprises asimple bundle tie device of the type used to tie bundles of conductorsin a cable.

A pair of radially extending locking ears or bosses 22, 24 are providedon two opposite sides of the body portion of the plug 2. The right-handsides of these bosses, as viewed in FIG. 5, are spaced inwardly from theplane of the mating face and the left-hand sides of these bosses definerearwardly facing shoulders 26 which cooperate with a locking ringdescribed below when the plug is mated to the receptacle portion of theconnector. It should be noted at this point that the shoulders 26 defineplanes which extend obliquely with respect to the axis of the bodyportion 6 of the connector rather than normally of this axis.

The receptacle part of the connector comprises a generally cylindricalbody portion 28 having cavities 30 extending therethrough from therearward side of the body portion to the mating face 36 thereof, thesecavities being of substantially the same shape as the cavities in theplug portion described above. Contact pins 32 are mounted in thesecavities and are secured to wires 38 which extend axially from therearward side 40 of the connector. The pins 32 have contact end portions34 of reduced diameter which extend beyond the mating face 36 so thatwhen the mating faces 10, 36 of the two connector parts move againsteach other, the end portions 34 of the contact pins will enter thesocket contacts 12 contained in the plug part 2.

A radially extending flange 42 is provided on the body portion 28 of thereceptacle adjacent to the mating face 36 and a cylindrical hood 44extends axially from the left-hand side of this flange as viewed in FIG.5 and surrounds the projecting ends 34 of the contact pins 32. The hood44 has an inside diameter which is substantially equal to, but slightlygreater than, the diameter of the body portion 6 of the plug and isadapted to receive the plug when the two parts are mated with eachother. In order to facilitate mating of the connector parts, thelefthand edge of the hood is advantageously beveled as shown at 46.

A pair of diametrically opposed hollow ribs 48, are provided on the hoodwhich define diametrically opposed slots or keyways 52, 54 on oppositesides of the hood. It will be noted that the slot 54 is relatively widerthan the slot 52 and that the boss or ear 22 is relatively wider thanthe ear 24. The ear 22 has a cross section which conforms to the crosssection of the slot 54 and the ear 24 has a cross section which conformsto the cross section of the slot 52. This arrangement polarizes theconnector parts with respect to each other and permits engagement onlywhen they are in the proper orientation.

A locking ring 56 is mounted on the external surface of the hood 44 forlimited rotation with respect thereto in order to permit coupling of thetwo connector parts i and to lock the parts in engagement with eachother in a manner described below. This locking ring is relatively thinand may be a simple stamped part of sheet metal or may be stamped ormolded from a relatively firm plastic material. Transversely extendingnotches 58, 60 are provided in the ribs 48, 50 to receive the innerperipheral portions of the locking ring as shown in FIG. 5, the width ofthese notches 58, 60 being slightly greater than the thickness of thelocking ring to permit rotation of the ring in a manner described below.

A first pair of diametrically opposed radially extending recesses ornotches 62, 64 are provided on the inner edge of the locking ring 56,the notch or recess 64 having a cross section conforming to the crosssection of the slot 52 and the ear 24, and the notch 62 having a crosssection conforming to the slot 54 and the ear 22. It will thus beapparent that when the locking ring is in an orientation such that thenotch 64 is in alignment with the slot 54 and the notch 62 is inalignment with the slot 52, the plug can be moved relatively into thehood 44 until the cars 22, 24

move past the plane of the rearwardly facing side of the locking ring.The ring can then be rotated through a slight angle after the connectorparts have been assembled to each other to locate surface portions ofthe locking ring against the rearwardly facing shoulders 26 of the earsthereby to lock the parts to each other. The transversely extendingshoulders 26 of the ears 22, 24 cooperate with the ring during suchrotation of the ring to draw the two parts of the connector into closeengagement with each other thereby to insure complete engagement of thecontact pins 34 with the sockets 12 contained in the plug portion of theconnector assembly. The ring 56 thus functions as a coupling ring aswell as a locking ring.

The locking ring can be assembled to the hood 44 of the receptacle byvirtue of a second set of diametrically opposed notches 66, 68. Thearcuate extent and the depth of these notches is sufiicient to permitaxial movement of the ring over the external surface of the hood andover the ribs 48, 50 when these notches are aligned with the ribs. Itwill thus be apparent that the notches 66, 68 are provided only for thepurpose of permitting assembly of the ring to the connector receptacle.

Locking ring 56 is also provided with an inwardly directed protrusion 70adjacent to the notch 68 which forms part of a detent device asdescribed below. The normal inside diameter of the locking ring issubstantially equal to, and slightly greater than, the outside diameterof the hood 44 so that the distance between this protrusion and theopposite inner edge of the ring is less than the outside diameter of thehood. It is therefore desirable to provide a first axially extendinggroove 72 on the external surface of the hood to permit relativemovement of the ring over the hood. After the ring has been assembled tothe hood as shown in FIG. 3, it is rotated in a clockwise directionuntil the protrusion 70 is moved into a second axially extending groove74 on the external surface of the hood, the hood portion being flexedand deformed slightly during such rotation of the ring to permit passagethereover of the protrusion 70. As shown in FIG. 2, the right-hand sideof the groove 72 has a relatively gentle slope towards the surface ofthe hood, as indicated at 78 to facilitate rotation of the ring from theorientation which is required for assembly (FIG. 3) to its position whenthe protrusion 70 is located in the groove 74 (FIG. 4).

When the locking ring 56 is in the orientation of FIG. 4 with theprotrusion 70 extending into the groove 74, the notches 62, 64 are inalignment with the slots 52, 54 and the parts of the connector can beengaged with each other. After such engagement, the ring can be rotatedfurther to locate surface portions of the locking ring against theshoulders 26 of the ears 22, 24, and to locate the protrusion 70 in ashallow groove 76 on the surface of the hood. The two grooves 74, 76 andthe protrusion 70 thus function as a detent means for releasablylatching the locking ring 56 in either of its two normal positions. Thering can be turned manually from either position to the other position,however, a slight force must be exerted on they ring so thatunintentional or accidental rotation of the ring is prevented.

The external surface of the hood 44 is generally cylindrical, however,it is desirable to provide a slightly reduced wall thickness in thishood on the path followed by the protrusion 70 when the locking ring isrotated from the groove 72 to the groove 74. It is also desirable toprovide a reduction in the wall thickness along the path between thegroove 74, 76 over which the protrusion moves when the ring is movedbetween its locking and unlocking positions. The external diameter ofthe hood should be such that the ring can be moved from the orientationor position it occupies immediately after it is moved onto the hood(FIG. 3) to the position it occupies when the protrusion is received inthe groove 74 only with some difficulty, for example by the use of apair of pliers or other assembly tool. If this is done, it

becomes virtually impossible to remove the ring from the receptacleportion of the connector manually and the parts will be held in theirassembled relationship. The dimensions of the parts should be such thatthe ring can be rotated between its located and unlocked positionswithout undue difiiculty, that is, without the aid of special tools, butthe resistance to rotation of the ring should be such that unintentionalor undesired rotation of the ring will not take place. These featurescan be achieved, for example, by shaving slightly the zone 80 of theexternal surface of the hood between the groove 72, 74 and shaving to aslightly greater extent the zone 82 between the grooves 74, 76.

As previously noted, the connector parts are advantageously molded of arelatively high grade plastic material. Suitable materials include Noryl(a modified polysulfone produced by the General Electrical Company), orpolycarbonate. These materials have good strength, are resistant toweathering, and are relatively firm or hard so that the connector partswill provide adequate protection for the contacts contained therein. Aspreviously mentioned, when the ring is assembled to the hood of thereceptacle, some slight flexure of the hood will take place during thefirst rotational movement of the ring, that is when the protrusion ismoved from the groove 72 to the groove 74. The material from which thereceptacle is molded should not be so rigid that it will crack underthis slight flexure. Many plastic materials, other than those mentionedabove, are commercially available which are suitable, from thestandpoint of their mechanical properties, for connectors in accordancewith the invention, for example, relatively firm nylon and semi-rigidpolyvinyl chloride.

A salient advantage of the invention is that substantially all of theadvantages of previously known high priced circular connectors areachieved even though the connector in accordance with the inventioncomprises only two molded parts and one additional part (the lockingring) which may be either molded or stamped and formed from sheet metal.By virtue of this fact, connectors in accordance with the invention canbe manufactured at a cost which is only a small fraction of themanufacturing cost for conventional circular connectors in which aninsulating insert is mounted in a metallic cylindrical shell member.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only.

What is claimed is:

1. An electrical connector assembly comprising a plug part and areceptacle part,

said plug part comprising a cylindrical plug body portion having aradially extending locking ear thereon adjacent to its mating side, saidear providing a rearwardly facing shoulder lying in a plane extendingtransversely of the axis of said plug body portion, said receptacle partcomprising a cylindrical receptacle body portion, a circular hoodextending axially from the periphery of said receptacle body portion onthe mating side thereof, said hood being adapted to receive said plugbody portion, said hood having at least one axially extending ribthereon, said rib being hollow and defining an axially extending slotopening into the area enclosed by said hood, said slot being adapted toreceive said ear,

a locking ring rotatably mounted on said hood, a transversely extendingrib notch in said rib, said ring having its inner edge portionsextending into said rib notch, said ring having a first radiallyextending ring notch extending from its inner edge, said first ringnotch having a cross section conforming to the cross section of saidslot, second radially extending ring notch in said ring, said secondring notch having a cross section sufficiently large to permit passageof said rib therethrough whereby said locking ring can be assembled tosaid receptacle hood by aligning said second ring notch with said riband moving said ring over said hood in the axial direction of said hooduntil said ring is disposed in said rib notch, and said plug part can beengaged with said receptacle part when said locking ring is in a firstrotational position in which said first ring notch is in alignment withsaid slot thereby to permit movement of said ear past said locking ring,and said locking ring can thereafter be rotated to a second rotationalposition in which surface portions of said ring are disposed againstsaid shoulder thereby to locking said plug part to said receptacle part.

2. A connector as set forth in claim 1 wherein said plug part and saidreceptacle part each comprise a one piece molding of insulatingmaterial.

3. A device as set forth in claim 1 including detent means effectivebetween said locking ring and said hood, said detent means beingeffective to latch said ring in either of two positions on said hood,said first ring notch being in alignment with said slot when said ringis in one position and said ring notch being out of alignment with saidslot when said ring is in its other position.

4. A device as set forth in claim 3 wherein said detent means comprisesa detent ear extending radially inwardly from the internal side of saidring and recess means in said hood adapted to receive said ear when saidring is in one of said positions.

References Cited UNITED STATES PATENTS 1,134,179 4/1915 Boyd 285-3621,200,118 10/1916 Keeler 285362 1,778,739 10/1930 Wheaton 2sss22,787,770 4/1957 Arson 339-63 FOREIGN PATENTS 4,272 1/1908 Great Britain285--377 MARVIN A. CHAMPION, Primary Examiner J. H. MCGLYNN, AssistantExaminer

